In known methods of determining the mechanical properties of coal, two different instruments are required. One such instrument comprises a pot for containing a sample of the coal to be tested, and a rotor which is rotatable in the pot. The rotor carries sacrificial elements in the form of radially protruding paddles. To test the coal sample, the rotor is rotated in the pot, without axial pressure being applied to the coal sample. The test is referred to as the Yansey-Gear test and yields results from which the abrasiveness of the coal can be determined. The other instrument comprises a plate and steel balls, between which a coal sample is ground. This test yields results from which the grindability (referred to as the Hardgrove index) of the coal can be determined. The results from the first test cannot be used to determine grindability of the coal, nor can the results of the second test be used to determine abrasiveness of the coal.
It is an object of the present invention to provide test apparatus by means of which both abrasiveness and grindability of a particulate material can be determined. It is a further object of the present invention to adapt such apparatus for use in pulverizing a particulate material continuously, on a production scale.